ISSN 1063-0740, Russian Journal of Marine Biology, 2017, Vol. 43, No. 2, pp. 111–117. © Pleiades Publishing, Ltd., 2017.
Original Russian Text © B.I. Sirenko, 2017, published in Biologiya Morya.
Two New Species of the Genus Leptochiton (Mollusca,
Polyplacophora) from North-Western Pacific
B. I. Sirenko
Zoological Institute of Russian Academy of Sciences, St. Petersburg, 199034, Russia
Received November 26, 2015
Abstract⎯Two new species of the genus Leptochiton, L. сommandorensis sp. nov. and L. incubatus sp. nov.
from north-western Pacific are described. Leptochiton сommandorensis differs from the congeners in having
radial rows of granules in the lateral areas of intermediate valves, unicuspid dental cap on major lateral teeth
of the radula, and dorsal scales with two ribs. Leptochiton incubatus differs from the congeners in having one
aesthete pore in each granule, a shallow depression between the central and lateral areas of intermediate
valves and between the antemucronal and postmucronal areas of the tail valve, and unicuspid head of major
lateral teeth of radula. This species is brooding.
Keywords: chitons, Leptochitonidae, Leptochiton, brooding, new species
The fauna of chitons on the genus Leptochiton in
the north-western Pacific is rather diverse. Eight spe-
cies of the genus (Leptochiton alascensis (Thiele,
1909); L. assimilis (Thiele, 1909); L. batialis Sirenko,
1979; L. belknapi Dall, 1878; L. kaasi Sirenko, 1990;
L. lukini Sirenko, 1990; L. rugatus Carpenter MS,
Dall, 1879, as well as L. hakodatensis (Thiele, 1909))
are known in this area . Three further species in the
North Pacific, Leptochiton japonicus (Thiele, 1909)
mentioned in  and  and Leptochiton cancellatus
(Sowerby, 1839) and L. alveolus (M. Sars in Lovén,
1846) from  are absent in the area under consider-
ation. Two species, collected in 1990 and described
herein, increase the number of Leptochitonidae of this
region up to ten species.
MATERIALS AND METHODS
The material was collected during 22nd cruise of
R/V Akademik Keldysh in 1990 at the bathyal and
abyssal depths of the north-western Pacific near the
Commander Islands and eastern Kamchatka (Russia).
The holotypes of both species and the paratype of
L. incubatus were preserved in 75% ethanol. Their
valves, armature of girdle and radula were boiled for
15 min in 7% KOH solution to remove all organic
material. Then the valves I, IV, V and VIII, half of the
girdle armature and half of radula were used for a study
with a FEI SEM Quanta 250, while the remaining half
of the girdle armature and radula were put in Canada
Balm to be examined under a light microscope. Type
specimens are kept in the Zoological Institute of the
Russian Academy of Sciences, St. Petersburg (ZISP).
Class Polyplacophora Gray, 1821
Subclass Neoloricata Bergenhayn, 1955
Order Lepidopleurida Thiele, 1909
Family Leptochitonidae Dall, 1889
Genus Leptochiton Gray, 1847
Chiton cinereus Montagu, 1803 (non
Linnaeus, 1767) = Leptochiton asellus (Gmelin, 1791)
fide Lovén, 1846, subsequent designation by Gray,
Leptochiton incubatus sp. nov. (Figs. 1–3).
Leptochiton sp. 1: Sirenko, 2013 : 148.
Leptochiton sp.: Sirenko, 2015 : 29.
Holotype (ZISP 2255) 6.5 × 3.5 mm;
1 paratype (ZISP 2256) 6.8 × 3.8 mm, both specimens
disarticulated, consisting of mounts of shell, armature
of girdle and radula.
North-western Pacific, near Kam-
chatka Peninsula, 53°27.9′–53°25.4′ N, 160°20.0–
160°21.5′ E, 1763–1815 m, pelite, mud and large peb-
The article is published in the original.